I definitely 2nd the spay thing above.
I have a very territorial rabbit as well (and she is spayed). I call it her "bun-ittude". Basically, what we have done is make her things, our things. It might be a little more difficult since she is older - but I would start by spending time with her when you feed her. Maybe feed her in a separate place (somewhere new) and sit with her while she eats. I'd also try switching up her home. If it's a NIC condo - maybe switch the floors around.
My bun also will take pellets as treats one at a time from us and will gently take them from our hands - which is awesome if you knew what a territorial terror she is. This has taken time but I feel like it really lets her know that we are her humans and need to be respected. The only time she gets aggressive now is when my boyfriend is torturing (/he thinks he's "playing") with her and she will nip. But - that's what he gets and that's a whole different story.
I'd try it - it takes a lot of time and patience but it makes for a better experience as a bunny owner.